Well it took some time but I got my centrifuge built, and did it for under $200. I am going to make a few changes so the finished product will be closer to $300 but worth every penny just the same.

The most difficult part to make was the rotor, pictured here:

It's a steel rotor made of four pieces.This is by far the toughest part to build and a good place to start.

1.We started with a large piece of 3/4" wall, 10"I.D., DOM tube that I found in a rem pile at my local metal supplier.

2. Then we chucked the tube in the lathe to cut it down to about a 6" length. We then 'trued it up' by recutting the outside and inside of the DOM to make sure it was exactly the same thickness all around. (This step is only neccessary if you plan to run excessive RPM to max out the centripital force. Lower speed rotors can likely get away without this step.)

3. Next we cut grooves in our piece of DOM with the lathe. I did this step to create a snug fit for two steel rounds that I got from Indestrial Metal Supply in Phoenix. Once pressed in they were were welded into place. (This step is not neccessary, I just wanted a tight fit. The rounds could have just been welded directly to the tube for low speed applications, although it is critical that the ends are cut as close to square as possible.)

4. The fourth piece is the hub located inside the rotor, I needed some thick steel to hold the motor shaft securely. (once again this shouldn't neccessary for lower RPM centrifuges.)

If I didn't have access to a machine shop I would have built a low speed unit using all the above pieces with a thick bottom plate. Once the rotor is welded I would take it to a local machine shop to have the welds cut smooth and a shaft hole with keyway slot cut in the exact center.

This would save a considerable amount of money in building your rotor since the machine shop would only charge a couple hours of shop time to make these simple cuts.

Once you have your rotor built you are well on your way to completing your centrifuge. I will post the rest of the steps, but I just wanted to cover the rotor first.

And for those of you that don't think a centrifuge is worth it, check this out: This is a befor and after of a single pass of 200 gallons of some very nasty oil. I had to stop to clean the rotor several times, but it was well worth it in the end.

Until I started 'fuging' I wouldn't have bothered with such heavily contaminated oil. Good stuff!

Dkenny, I don't have any diagrams, but the concept is pretty simple. I have a feed tube that drops into the rotor through that hole on top (where the beer is). As the rotor spins it forces the WVO to the inside wall by centripital force (about 2000G's for this unit).

The extreme G-force causes the heavier particles (and liquids like water) to get stuck to the inner wall and the lighter materials i.e. now clean WVO or biodiesel to build up until the rotor is full and it comes out the 'beer hole' much like this test we did below:Here we were testing the unit for the first time with City of Tempe tap water. It ran for one hour. The rotor was full of a brownish/black sludge (which would be the heavier particles) when finished.

In the pic above you can see the water (in this case the lighter material)escaping out our 'beer hole' watering our lawn

I have since put together a container to 'catch' this mist (now oil based) and pump it into one of my storage containers.

And thats basicly the way how a rotor type centrifuge works. I will get into more detail on the bearing set / shafts / couplers / bushings / motor / etc as this thread continues.

Its a bit much to put up all at once, also I want the community to help come up with better ideas on how the average bio-brewer can make one at home for cheap.

Ryan, yes you can see the material building up in the bowl. Its really neat looking. It looks like a wall of oil slowly moving to the 'beer hole'

This unit sits in a container that houses the rotor/bowl and stand with the electric motor outside (to prevent it from getting soaked in oil). I used a piece of Lexan for the top (much like plexiglass) so I can monitor whats going on in the container.

It's really easy to use once I get it to full RPM. If I notice sudden changes in the color of the mist escaping from the rotor then it is probably about full and needs shut down for a cleaning. Once done, I fire it back up and let it continue cleaning my WVO.

I am setting it up this morning to remove water from some badly contaminated oil. I expect two quick passes should get it to pass HPT and vapor tests. Guess I'll find out later today if my assumption is right

dkenny, there is a fella on youtube that made one out of wood, the link is here:wood centrifuge

Its pretty neat, although it would scare the hell out of me to use

For my centrifuge we built a lower bearing housing (just under the rotor) using 72 Chevy Malibu tapered wheel bearings (about $7 at the local checker auto parts store). They are such overkill for this setup that slight out of balance issues should be overcome.

I have a container that surrounds the rotor and base of the centrifuge. Just for a quick use I cut a 55 gallon steel drum in half and used lexan (a lot like plexiglass) as a lid so I could see what was going on in the rotor.

It works ok, but is leaky. Im building a new container and will post pics as it comes along.

Steel is a readily available material and almost anyone with a cheap mig welder could build a unit like this. I would probably stick with steel for most situations. Our next one will likely be aluminum but I have a good TIG welder.

Steel is a readily available material and almost anyone with a cheap mig welder could build a unit like this. I

How about any old steel wheel? They are already balanced to handle some level of high rpm: whatever a wheel hits at 80-90mph.

Better yet; a drum brake. The shape is already about right. If you can get your hands on just the right model, it will have wheel stud pressed through it already and be moisture-tight.

A drum can be difficult to weld on because they are cast. Its not like welding onto an engine block but it does make for some weak points (not a good quality in a centrifuge )

An steel wheel could work. at 90MPH it is rotating at about 1500RPM (thats assuming a standard size car or light truck tire of about 24"). A 15" rim would push some pretty high G's hooked up to a direct drive 1750RPM motor.

The advantage would be the bearing housings would be readily available, just buy the spindle and bearing set for that wheel. The disadvantage would be having to make it liquid sealed. If the top lip were welded in the right place the wheel could still be put on a tire balancer and rebalanced after welding.

Its a thought, and one my buddy Neil suggested it more than a few times. Although his idea was to buy a wheel blank (made of aluminum) with an extreme offset to make for a deeper bowl. It would save us some machine time on the new 'fuge'.

It looks like I might a have project to make this fall winter. I've wanted a CF for a long time.

I was thinking about making a wood one.. I have a wood lathe so spinning to at 3600 is easy..then fiberglass several layers on the outside. using the wood bowl mold..make it made a little taller, maybe 10 inchs..turn a pulley into the bottom..run 6 wheel on the sides in 2 layers of 3. to help counter the force from the pulley..

not as safe as I would like, but what if 3 wheel( inline skate type) were mounted around the outside about 1/3 down from the top.

oil collection would happen above this area..

-dkenny

This message has been edited. Last edited by: dkenny, September 02, 2009 08:51 PM

Originally posted by dkenny:It looks like I might a have project to make this fall winter. I've wanted a CF for a long time.

I was thinking about making a wood one.. I have a wood lathe so spinning to at 3600 is easy..then fiberglass several layers on the outside. using the wood bowl mold..make it made a little taller, maybe 10 inchs..turn a pulley into the bottom..run 6 wheel on the sides in 2 layers of 3. to help counter the force from the pulley..

not as safe as I would like, but what if 3 wheel( inline skate type) were mounted around the outside about 1/3 down from the top.

oil collection would happen above this area..

-dkenny

I like the fiberglass reinforced wood idea, if that guy on youtube can use straight wood and not have it explode then fiberglass reinforced should work even better if applied correctly.

The outside rotor wheels is a good idea as well to add stability and absorb a lot of the built up energy forced to the sides of the rotor, although I bet you won't need it for an application running these G's.

if all goes well I've on made from freon tank this weekend. I'm wondering if the tank is too tall.

I mount the tank to the blade spindle from the large riding lawn mower. now I just need to build the box around it and figure out a motor/pulley setup..the spindle has a pulley on the other end from the blade.

All home brew centrifuges need to be operated inside a substantial metal scatter shield (like steel drum, at least until proven absolutely safe and reliable. At the speeds a functional CF operates, any significant wobble or imbalance or weakness can turn your centrifuge into a grenade, shrapnel and all.

Excellent discussion,

Please carry on.

troy

Location: north america somewhere close to the midwest, or not | Registered: May 29, 2004

I found it and was playing with it because the AC motors that i have are 1725..sure I can use pulleys to change the speed. I was wondering what the g's were using 1800 instead of 3600..

I need to work on my balancing..troy was right...mines not balanced and I haven't put the extra wheels on yet..I'm wonding if the tank is 'round'..if not I might have to make a wood one..atleast I can test this at high speed on the lathe..just playing with it a less than 1725..maybe 1200rpm..a guess because of pulley sizes..I had it spinning untili added 16oz of water..then it ran apart..not damage of injury. next time I have the off sw closer..

I wish the youtube wood lathe person would post details about the bowl..what wood? single chunk? laminated?

phooy...the tank isn't round enough..and would be too hard to make round.

but I did have an idea for the wood version..plywood..cabinet grade..these contain lots of thin layer already glued together..now I just need to glues several layers together. I thought about rotating each layer by 30 degrees from the last..something to work on..

Just remember, balance is ultra critical, these things will, repeat, will, grenade at centrifuge speeds, commercial centrifuges that have been balanced to near perfection still grenade now and then, so use extreme caution and don't let anything you don't want large pieces of shrapnel sticking out of near it.